Here is a workaround using Tasker:
Profile (or Trigger)
Create a Profile which allows sending to contact with the missed call:
- Goto Profiles Tab and click the "+"
- Event >> Phone >> Missed Call
- Tap back to exit from this window
You will notice as soon exit, you will be prompted to link this to a Task
- Scroll all the way up the Task list select "New Task + "
- You can name this Task SendSMSmc or anything.
- Click "+" to add new Action
- Phone >> Send SMS [Number:%CNUM Message ( e.g I am currently busy at the moment, I'll call later)
- Tap back to exit from this task
- Press back all the way to exit (Your task is saved)
Explanation: When a call is received, and even if you are not able to answer it, the "Missed Call trigger" allows Tasker to send a message containing the body test: "I am currently busy at the moment, I'll call later" to the missed call number" where %CNUM is the missed call number.
Hope this helps other users well